Cryptorchestia, Lowry, J. K. & Fanini, Lucia, 2013

Lowry, J. K. & Fanini, Lucia, 2013, Substrate dependent talitrid amphipods from fragmented beaches on the north coast of Crete (Crustacea, Amphipoda, Talitridae), including a redefinition of the genus Orchestia and descriptions of Orchestia xylino sp. nov. and Cryptorchestia gen. nov., Zootaxa 3709 (3), pp. 201-229 : 204-205

Cryptorchestia gen. nov.

Type species. Orchestia cavimana Heller, 1865 .

Etymology. Crypto- from the Greek for hidden and referring to this unknown taxon within the genus Orchestia .

Diagnostic description (based on male). Eyes present. Antenna 1 short, not longer than article 4 of antenna 2 peduncle. Antenna 2 peduncular articles slender; peduncular article 3 without ventral process. Labrum without robust setae. Mandible left lacinia mobilis 4-dentate. Maxilliped palp article 2 distomedial lobe well developed; article 4 reduced, button-shaped or fused with article 3. Gnathopod 1 subchelate; posterior margin of merus, carpus and propodus each with lobe covered in palmate setae. Gnathopod 2 subchelate; merus and carpus free; dactylus slender distally. Pereopods 3–7 cuspidactylation not known. Pereopods 6–7 not sexually dimorphic, both without row of short setae along posterior margin of dactyli. Pleonites 1–3 without dorsal spines. Pleopods 1–3 biramous, well developed. Epimera without vertical slits. Uropod 1 outer ramus slender, with marginal robust setae. Uropod 3 well developed; ramus subequal in length or slightly longer than peduncle. Telson incised, with 5–10 robust setae per lobe.

Included species (9 species). Cryptorchestia canariensis ( Dahl, 1950) (Gran Canaria, Canary Islands); C. cavimana ( Heller, 1865) ( Cyprus) ; C. chevreuxi (de Guerne, 1887) (Fayal Island, The Azores); C. gomeri (Stock, 1989) (La Gomera, Canary Islands); C. guancha ( Stock & Boxshall, 1989) (Tenerife, Canary Islands); C. kosswigi ( Ruffo, 1949) (east Turkish coast); C. mateusi ( Afonso, 1977) (the Azores); C. monticola ( Stock & Abreu, 1992) (Madeira) ; C. stocki ( Ruffo, 1990) (Gran Canaria, Canary Islands).

Remarks. Cryptorchestia differs from Orchestia in male gnathopod 1 which has palmate lobes on the merus, carpus and propodus and in generally having fewer robust setae (5–6) on the telson. The species in Cryptorchestia are all terrestrial species associated with freshwater. Species of Orchestia occur in the supralittoral marine environment. Cryptorchestia appears to be similar to Traskorchestia Bousfield, 1982 , a marine supralittoral group from the North Pacific Ocean in which at least the type species ( T. traskiana (Stimpson, 1857)) has a palmate lobe on the merus of male gnathopod 1.

The type species, Cryptorchestia cavimana ( Heller, 1865) is seriously in need of redescription; however, the original illustrations of Heller undoubtedly depict the characters of the genus. Even though C. monticola apparently does not have a palmate lobe on the merus of male gnathopod 1, it fits into this genus based on overall character assessment and appears to be most similar to C. gomeri which does have this particular character. Stock & Boxshall (1989), based on logical arguments, considered Orchestia mateusi Afonso, 1977 to be a junior synonym of C. chevreuxi . It also does not have the palmate lobe on the merus of male gnathopod 1, but appears to be in the genus. It differs from C. monticola in having an attenuated dactylus on male gnathopod 1.

Herbst & Dimentman (1983) considered that the freshwater talitrid Orchestia tiberiadis Lortet, 1883 , known from Lake Kinneret (Sea of Galilee), is a synonym of C. cavimana , based on advice from G. Karaman. Karaman (1978) had earlier considered that the Orchestia tiberiadis Lortet, 1883 was a senior synonym of C. kosswigi Ruffo, 1949 . Karaman came to this conclusion based on the similarity of the male second gnathopods and the proximity of geographic locations. Bellan-Santini (1993) accepted this synonymy with reservation. The male dactylus of O. tiberiadis and C. kosswigi appears to be very long (reaching nearly to the proximal end of the posterior margin of the propodus), an unusual character state. But in all other aspects O. tiberiadis is undescribed so that, for the timebeing, it must be considered as dubious and the species from Israel remains undetermined. In a further complication Herbst & Dimentman (1983) imply that there is only one species in Israel, characterised by a short dactylus on male gnathopod 2, but this seems improbable based on the illustration of O. tiberiadis , by Lortet (1883) which shows a long dactylus.

Cryptorchestia mateusi fits into the genus except that it apparently does not have a plamate lobe on the merus of male gnathopod 2. But it fits in no other genus. For this reason it is placed into Cryptorchestia .

We include C. kosswigi in the genus. In the illustrations of Ruffo (1949) and Bellan-Santini (1993) there is a small lobe on the merus of male gnathopod 1. This character, coupled with its apparent preference for freshwater lake habitats (Karaman 1978) indicates that this species belongs in Cryptorchestia . The mouthparts are not known for the species.